Satellite observations show that the world's major ocean currents have been shifting poleward over the past four decades. However, this trend is masked by strong natural variability, making it difficult to attribute the shift to human activities or to project how far ocean currents may move in the future. Reconstructing past ocean current migrations is therefore critical. The Last Glacial Maximum (LGM), characterized by substantially lower atmospheric CO₂ concentrations than today, offers a particularly valuable geological analogue for understanding how ocean currents respond to CO₂ forcing.
Foraminifera are widely distributed in the ocean. Among them, the planktonic species Globorotalia truncatulinoides (GT) migrates vertically throughout its life cycle, making it highly dependent on warm, thermally uniform water masses found only within subtropical water， where downwelling dominates. By tracking changes in GT abundance across sediment core samples from multiple sites in the North Atlantic, we found that certain sites previously suitable for GT habitation no longer supported GT populations during the Last Glacial Maximum (LGM). The retreat of the GT distribution boundary differs from the modern distribution boundary by more than 600 kilometers, suggesting that the North Atlantic Current may have shifted northward by approximately 600 km since the LGM.
Numerical simulations support these findings. During the LGM, both lower atmospheric CO₂ concentrations and North Atlantic freshwater forcing drove the equatorward contraction of the North Atlantic current, substantially reducing its northward heat transport. This, in turn, favored the persistence of cold high-latitude climates and the stability of ice sheets over North America and Northern Europe. Together, the proxy and model evidence demonstrate that ocean current migration is a highly dynamic feature of Earth's climate history, and our reconstructed record provides an important benchmark for projecting the magnitude of future displacement.

North Atlantic Current,Last Glacial Maximum,migration